Mark Thompson, the director general of the BBC, went on the offensive against James Murdoch and other critics of the public broadcaster, effectively accusing News Corporation of lapses of integrity and warning that the collapse of the BSkyB takeover was not an excuse to start a debate about the scale and scope of the BBC.

Noting that the "broader debate about the future media landscape must not deflect us from the most obvious and urgent matters arising from the News of the World case … matters of personal conduct and criminality, and above all of ethics and values," Thompson proposed recasting Murdoch's 2009 conclusion.

"If James Murdoch was giving his lecture this year," Thompson writes, "I'd suggest he amended only one word in that final sentence. The only reliable, durable and perpetual guarantor of independence is not profit. Nor who you know. Nor what corners you can cut. It's integrity."

The BBC boss also chose to counter remarks made by David Cameron in July to MPs, when he detailed the terms of the public enquiry into phone hacking and media standards, to be conducted by Lord Justice Leveson. At the time Cameron said: "Above all we need to ensure that no one voice, not News Corporation, not the BBC , becomes too powerful" and that "there did come a point in recent years that the income of the BBC was so outstripping that of independent TV there was a danger of BBC News becoming rather dominant".

Thompson writes that Cameron's facts are wrong, that the "BBC today takes a smaller share of UK broadcast revenues than at any time in its history" and that the new licence fee settlement will mean further cutbacks. "It's impossible to look at the facts and still argue that the BBC represents a growing threat of economic dominance," he added, later noting that BSkyB's £6.6bn turnover means that the satellite broadcaster is "already by some margin the largest player" in British broadcasting compared with a BBC with a turnover of £5bn.

The BBC boss also writes that one reason the broadcaster's output is popular is that viewers "trust it more than other sources" and said for that reason alone it would make no sense to try to cut it back further in response to the hacking scandal. "If policy-makers begin to regard high levels of public trust as a problem to be corrected, we really are in trouble".

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